According to the Bible, what was the time span between Adam’s creation to the Flood?

1,656 years.

Genesis 5:1-29 and 7:6 outlines this:

From Adam’s creation to the birth of Seth:  130 years

Then to the birth of Enosh:                          105 years

To the birth of Kenan:                                   90 years

To the birth of Mahalalel:                               70 years

To the birth of Jared:                                     65 years

To the birth of Enoch:                                    62 years

To the birth of Methuselah:                            65 years

To the birth of Lamech:                                187 years

To the birth of Noah:                                    182 years

To the Flood:                                               600 years

Total:                                                      1,656 years